The objective of this research is to evaluate the costs and health benefits (in terms of reduced cancer mortality) of alternative radon reduction strategies, and to compare the cost-effectiveness of radon control with that of programs intended to reduce the principal cause of lung cancer, cigarette smoking. Specifically, the principal aim of the research is to determine which of numerous alternative approaches to radon control appears to be most efficient from a social perspective, i.e., which produces the most reduction in cancer mortality for a given expenditure of societal resources, based on current understanding of the health effects of radon. A secondary aim is to evaluate the relative merits of society's investing its scarce cancer prevention and control resources in radon testing and mitigation, in comparison with programmatic efforts directed at cigarette smoking prevention or cessation. Cost-effectiveness analysis (CEA) constitutes the method of the research. The fundamental analytical tool for the CEA will be a computer model designed, using the methodology of BEIR IV, to estimate overall mortality, lung cancer mortality, and average life expectancy under varying degrees of radon and smoking exposure (and hence reductions in each exposure from current levels). The model will apply to cohorts distinguished by age, sex, and smoking status. For different radon and smoking control programs, the model will also estimate intervention costs (fixed and variable, occurring immediately and over time), thus permitting calculation of cost-effectiveness. Given the numerous uncertainties pertaining to the health effects of radon (including the nature of the radon-smoking interaction), costs of intervening, etc., the study will rely heavily on the use of sensitivity analysis. Sensitivity analysis will permit determination of which findings are robust. In addition, it will identify those areas of uncertainty most deserving of further research to refine understanding of radon's health effects needed to evaluate alternative methods of control.